quota: honor quota type in Q_XGETQSTAT[V] calls

The code in quota_getstate and quota_getstatev is strange; it
says the returned fs_quota_stat[v] structure has room for only
one type of time limits, so fills it in with the first enabled
quota, even though every quotactl command must have a type sent
in by the user.

Instead of just picking the first enabled quota, fill in the
reply with the timers for the quota type that was actually
requested.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>